(a) Field of the Invention
The present invention relates generally to a caster, and more particularly to an improved brake for casters.
(b) Description of the Prior Art
Casters enable tables, chairs, etc., to move along surfaces with convenience. They are also equipped with brakes to stop their movement when desired to keep them fixed in position. With reference to FIG. 1, a conventional caster is comprised of a caster frame 1, having a through hole 1A. A roller 2 is pivotally provided at both sides of the through hole 1A. The inner circumference of the roller 2 is provided with a plurality of teeth 2A. The rear side of the caster frame 1 is provided with a rotary shaft 3 capable of free rotation. The bottom end of the rotary shaft 3 is fixedly provided with a gear 4. The front side of the caster frame 1 is pivotally provided with a trigger element 5 that can be pulled upwardly or downwardly. A stop element 6 is pivotally disposed below. The stop element 6 is punched into a V-shape having a pivot 6A in the middle, both sides or arms thereof being capable of swinging movement about the pivot 6A. The left end of the stop element 6 is bent upwardly to form a forked projecting insert portion 7 which may engaging the teeth at both sides of the gear 4. The right end of the stop element 6 is bent to form a support portion 8, an elastic plate 9 being disposed at the back side of the support portion 8 an integrally punched therewith. A spring 9A is also disposed at one side of the support portion 8 to provide the support portion 8 with a lateral resilient force. When the trigger element 5 is pulled upwardly, the support portion 8 compresses the elastic plate 9. When the trigger element 5 is pulled downwardly, releasing its force on the support portion 8, the resilience of the elastic plate 9 will push it upward to engage with the teeth 2A of the roller 2 for positioning purposes. However, in actual operation, since the stop element 6 is supported at the pivot to urge upwardly, it may deform in shape due to metal fatigue so that the insert portion 7 cannot easily align with the gear 4. Furthermore, the compression pitch of the elastic plate 9 may be too small so that the reset tension is unstable and inadequate, thus the stopping effects on the roller 2 and the gear 4 of the rotary shaft 3 are not good. The stop element 6 may easily break due to metal fatigue through prolonged use.